UnderNote Stories
by Errand Girl
Summary: A collection of oneshots that take place during the two year gap between Light's fall into the underground and her reunion with the Task Force.
1. Sanel

Light stared at the tiny bundle in Sans' arms. The little horned skeleton was wrapped in a violet blanket, her light blue eyes barely open. Light pursed her lips, looking up at Sans, uncertainty written all over her face.

"What... What if I drop her? Or hurt her, or...?"

"Light," Sans interrupted seriously. "She's barely awake. You are the kindest, sweetest, most gentle human I know. Nothing bad 's gonna happen. Sanel needs to know that you're part of the family too."

With that said, he placed the baby skeleton in Light's trembling arms. As Light held the tiny infant, she felt her anxiety slowly melt away. Sanel looked up at her and gave a small, innocent smile. Light's eyes felt hot, and they were starting to sting.

"Ya see, Sun-Light?" Sans said smiling. "She already loves you."

Light's heart swelled to the point she thought it would burst. Hot, wet tears slipped down her face, and she couldn't look away.

"He... Hehe..." Light smiled at the 'Baby Bone'. "H-hey, Sanel. I'm Light. Your big sister."

 _So... this is what it feels like_. Light thought as she pulled Sanel closer. This feeling of warmth, joy, protectiveness. _This is what it's like to be a big sibling._


	2. Nightmare

Light looked around her nervously. The monster village was eerily quiet. Not a single monster was out, and on such a nice day, that was not a good sign. She walked down the path to home, softly calling for her family.

"Mum? Dad?" She called quietly, her throat dry. "Papyrus? Undyne? Anyone?"

Light froze as she felt something crunch underfoot. Jumping back, she looked down at what she'd stepped on. She shrank away in horror as she saw a small pile of dust there. Her body began to tremble as terrible imaged began to play in her mind.

"M-Mum?!" Light borderline screamed, panic gripping her heart. "Dad! This isn't funny you guys! Answer me!"

"Sun-Light!"

Light spun around, her ponytail whipping her face. There, standing behind her, was Sans. His face was a mixture of worry and relief. He looked slightly out of breath.

"Dad!"

She ran to him, relieved that she'd found someone, but scared that he was the only one. The father and daughter held each other for a few moments, before pulling apart. Light looked up at Sans, eyes still panicked.

"Dad, what's going on?" She asked. "Where's mum? Sanel? Paps?"

"I don't know kiddo." Sans said, as he began to pull Light away. "Sanel is at the lab with Alphys. I don't know where everyone else is."

Light remained silent as she let Sans lead her away. Her mind was reeling. What could have happened to the rest of her family, all of her friends?

When they finally arrived at Alphys' new lab, Sans gave her a little push towards the door.

"Hide in there with Al and Sanel," he told her. "You'll be safe there."

Light turned to him in shock. "What? No! I'm going with you. I want to help."

"Light," Sans said sternly. "We don't know what's going on. If I lost you..."

He trailed off, but the message was clear. Sans thought the village was under attack. That just made her more determined to go with him.

"Dad, I-"

"Light, behind you!"

Light spun around to face what had startled her father. She only had time to catch a glimpse of something metal and a blur of brown clothing, before Sans was blocking her view. Blocking her attacker.

"Dad!" She screamed in shock and fear.

She surged forward, as Sans fell back. Tears stung at her eyes as she stared at the deep, red gash in his chest.

"No... Nononononono!" She muttered, panic pumping though her veins. "Dad. No. Don't..."

"He... I'm... sorry, kiddo." Sans apologised. "Looks like... I won't be... there for you anymore."

"Don't talk like that." Light said, trying to sound encouraging. "You're not going anywhere. You... You can't..."

Sans smiled gently at the girl that had been his daughter for the past two years. Tears were streaming down her face in a torrent. She was trying to deny it, but she knew he was dying. He could already feel himself dusting.

"What... What am I going to tell Alphys? Sanel?" Light sobbed, holding Sans close. "Dad, please. You can't... You can't leave us. Daddy..."

"I love ya, Sun-Light..."

Light watched with blurred vision, as Sans turned to dust in her hands. Pained sobs wracked her form as she formed her hands into fists, Sans' dust slipping through her fingers, as she held it close to her chest. In the background of her awareness, she could hear laughter, loud, crazed, maniacal laughter that she recognised all too well.

Kira.

* * *

"...t"

"...Light."

"Sun-Light!"

Light's eyes flew open as she bolted up right. She was shaking and covered in sweat, her heart was pounding wildly and she was breathing hard. She felt something touch her shoulder and flinched away, turning to face... Sans.

"Whoa, whoa, easy there, kiddo," Sans said, trying to be soothing.

"D-Dad?" Light's voice sounded soft and distant, even to her.

"Yeah, it's me, kiddo." Sans said gently. He reached out a bony hand and carefully patted her head. "You had us all worried there for a bit."

"'Us'?" Light asked in confusion.

"Yeah," Sans said, pointing a thumb at Light's door. "Us."

Light looked at where he was pointing, to see all of the monsters she loved the most. Papyrus, Mettaton, Aphys, Undyne, Asgore, Toriel with Sanel in her arms, even Flowey was there. They all came into the room in a flood, asking Light if she was okay. Light looked away for a moment, to try and compose herself, before turning back to her family with a smile.

"I'm alright, everyone." She said assumingly. "It... was just a bad dream."

Light was caught off guard as Sans pulled her into a sideways hug.

"Whelp," He said smiling. "I think I'm gonna stay right here. I'm up now anyway."

"THE GREAT PAPYRUS SHALL ALSO STAY." Papyrus said in his usual cheery tone. "FEAR NOT, DEAR LIGHT, FOR I SHALL PROTECT YOU FROM THESE NIGHTMARES, WHICH INVADE YOUR SLEEP."

One by one, everyone said that they were going to stay there with her. In the span of just a few minutes, all of them were curled up on large piles of blankets on the floor of Light's room. Surrounded by the warmth, Light felt safe. She was sandwiched between Toriel and Sans, with everyone else spreading out in a small circle. Her dream still had her, a little scared, but in that moment, surrounded by the ones she loved, she could forget it.

For a little while.


	3. Back story

After Light regains her memories at the end of the Yotsuba arc, she became disgusted and fights with her other half. In a last ditch attempt to stop Kira for good, she goes to Mt. Ebott and jumps down a large hole. However, she hit her head really hard during the fall, and as a result lost all of her memories. So she didn't know who 'the voice in her head', who 'Kira' was.

Kira had claimed to be her ally. That they were there to protect her from the monsters that lived in the Underground. After the run in with Flowey, Light began to believe what Kira had said, and placed her trust in them, killing any monster that attacked them. Even Toriel.

However, when she encountered Papyrus, and he tried to spare them. Light began to question what they were doing. She wanted to spare Paps, and tried to convince Kira of the idea as well. She was about to use MERCY, when Kira took control and killed Paps anyway. This act of pure cruelty made Light realise that Kira had been lying to her. The realisation of what they had done, and that no one would offer her a chance again, decimated Light's HoPe. She gave up.

Kira continued to kill all of the monsters in the underground, until the Judgement Hall, where Sans stepped in. Watching Sans fight back against Kira, slowly began to rekindle Light's HoPe. She began to think that, maybe, Kira could be stopped. Her HoPe grew to the point where she was openly cheering him on. When Kira attempted to kill Sans after he fell asleep, Light, in an act of defiance, seized back control and stabbed herself through the chest. In her final moments, before she RESET everything, She apologised to Sans and promised that she was going to fix everything.

RESETing the timeline, Light went through the True Pacifist run, freed the monsters and never looked back. Not seeing any signs that anyone was looking for her, Light came to the conclusion, that either she didn't have any family, or they didn't really care about her. She is now Toriel's daughter, and Sans acts like a doting father to her. The two monsters got married several months after their escape from Mt. Ebott.

It has been two years since Yotsuba and freeing the monsters. Light is acting as their ambassador, but has yet to make a public appearance. What do you think would happen if she accidentally met up with L, when Sans tries to use his shortcuts while tired?


	4. Appearance doesn't matter

"Sun-Light! I'm back." Sans called trough the house. "Your mum and Sanel are gonna be late, today. So, it's just us for dinner."

Sans looked around for his daughter. Usually, she came bounding up like a puppy, but today, there was no sign of her. He looked at the clock, she couldn't still be at the government building at this hour, and she didn't say anything about visiting a friend. He began to walk up the stairs to her room, calling her name.

When he reached her door, he opened it carefully and looked in. Light was lying in her bed, the covers pulled up to her chin. She looked like she was sleeping, but there was something off. Sans could feel it in the air. Looking closer, he saw the Light was shaking violently, tears streaming down her face. Sans could have sworn his soul froze. He rushed in and to Light's side.

"Light! Light, what's wrong?" He asked hurriedly.

"Mmm..." Light cracked her eyes open and forced a smile. "Howdy, Dad. Welcome home."

Sans frowned and checked Light's HP. It was down to ten, that wasn't good. But, she didn't seem to have a fever, so that left injury.

"Alright, Sun-Light." Sans said, rolling up his sleeves. "Show dad where it hurts."

"N-No, no. Dad, I'm fine. I'm just... tired from work." Light insisted.

"That's cute." Sans said with a roll of his eyes. "Now, show me what's wrong."

"D-Dad, really," Light insisted. "I'm fine. Where are mum and Sanel?"

"They're going to be late today. Now, don't change the subject." Sans said seriously. "Show me what's wrong, Light."

"Dad," Light said, eyes almost pleading. "I'm fine. I'm just feel tired."

Sans frowned. This conversation wasn't going anywhere. He was going to need to take more drastic action.

"Okay," he sighed. "No more, nice guy."

Saying that, he grabbed a fist full of the sheets and pulled them off in a rush. Light noticed what he was about to do, and made to stop him, only to scream as pain seared through her shoulder. She sobbed softly as the burning pain continued.

"It... It had just stopped hurting." She said between sobs. "Why would you do that?"

Sans stared at the ugly, bright red burn on Light's left shoulder. Her sleeve had been mostly burned away, leaving the damaged skin completely exposed. The cloth surrounding the burn was charred black and was likely attached to the skin beneath from the heat. Sans was horrified. How did this happen? Why?

"Light," Sans said softly. "Why would you hide that from me?"

He leaned forward, reaching out to the wound, only to have Light flinch away. Sans sighed, clearly Light was reluctant for help. Why was she always so difficult? Activating his magic, he shifted Light's soul blue and pulled her close, using his blue magic to keep her still.

"D-Dad! Stop!" Light shouted, slightly panicked. "Dad, it hurts! Stop it!"

"Shh," Sans shushed gently. "Light, calm down. I'm not gonna hurt you, but I need to look at your shoulder."

"But..." Light looked up at him, teary-eyed.

"No 'buts'." Sans stroked her hair gently, trying to calm her. "Just relax."

The familial gesture did its job. Light slowly began to relax. With her now distracted, Sans added a little healing magic to help ease the pain. Now that he could get a better look at it, he could tell that the burn was fairly new. No more than thirty minutes old.

"Light," he said, trying to stay calm. "Tell me how you got that."

"Am... Am I in trouble?" Light asked nervously.

"He. That depends on how quickly and honestly you explain what happened."

Light sighed. "I was trying to make tempura and my clothes caught fire."

"On your shoulder, form that position? Sure~." Sans said sarcastically.

"Fine. I was mucking about with fire magic. I know you said not to use it without you or mum, but-"

"The truth, Light." Sans said sternly. "That's strike two."

"Okay! Okay..." Light sighed in defeat. "I... I was in the Underground. Hotlands, specifically. I got careless and my shoulder got burnt."

Sans was confused. "Hotlands? Light, why would you go to Hotlands? What were you doing?"

"I..." Light bit her lip. "I was going to the 'True Lab'. I wanted to see if..."

"If what, Light?" Sans insisted.

"If there was a way to turn me into a monster."

Sans stared at Light in shock. What in the world was she talking about?

"Every time I'm at work, everyone keeps asking me how I'm the ambassador for the monsters when I'm a human, or how you and mum could ever be my parents. Sometimes, they even imply that you guys kidnapped me." She sniffed, tears welling in her eyes. "I hate it! What do they have against a monster family adopting a human? I thought, 'if the problem is that I'm a human, when you're monsters, then maybe all I'd have to do is change into a monster'. I thought there might be something in the True Lab. But, all I ended up with was a bad burn."

"Light," Sans pulled her into a tight embrace, mindful of her burn. "Don't you _ever_ talk that way, again! Now, you listen, and you listen close, Light. You are as much a part of this family as me, your mum, or Sanel. We all love you so much and are so proud of you."

Light was trembling in Sans' arms, tears once again streaming down her face. Sans gently stroked her hair as he held her.

"Light, promise me that you'll never do something like this ever again."

"But..."

"No, buts."

"But, I'm..."

Sans pulled back a little, looking Light dead in the eyes. "I'm not looking for excuses or explanations, Light. Do you have any idea what I would have done if we'd lost you? How it would affect your mother, Papyrus, Sanel... _me_?"

"I... I didn't really think that far ahead." Light admitted. "I just... I can't stand them talking about you all like you're... you're..."

"Monsters?" Sans smiled. "Light, you can't combat how a whole world thinks, all by yourself. I'm sorry that you've had to deal with that kind of prejudice at a place where you should feel accepted. But, monsters have been the bad guys of stories for generations; you can't expect that to change overnight. And, as for you not being a monster. Whoever said you had to be? You are not a part of this family because of what you are, Light. You're a part of this family because we love you. What you are on the outside ain't got anything to do with it."

Light squeezed Sans tightly. "I love you, Dad."

Sans smiled warmly as he held his child. "I love you too, Light. But," he frowned. "We still need to treat that shoulder of yours properly, and you're still grounded for doing something so stupid and reckless."

"Dad, seriously?! I'm at _least_ nineteen already."

"Don't care, you're still grounded."

"Ugh!"


	5. The Day You Fell

"Mum, dad, I'm home!" Light called as she walked through the front door of her home. "And I would really like an explanation as to why the shopping list called for ten packs of sparklers, two large packs of streamers and twenty packets of Chocolate covered macadamias." She paused at the macadamias, looking them over before putting them back in the bag with an embarrassed mumble. "...Not that... I'm complaining."

She looked around the room, trying to find any sign of her family, only to find the place completely empty. She frowned in confusion. She thought she'd spoken loud enough to be heard anywhere in the house. Walking further in, she continued to call for them, but sill no one responded. She grumbled as she walked to the kitchen.

"Geez, where is every..." She trailed off as she stood in the doorway.

There in the kitchen, was her mum, dad, Uncy Papy, Aunty Ton-Ton, Alphy, Undyne, Asgore, Monster Kid, and Flowey. Each of them was putting up some kind of decoration, or placing a rapped box on the table. They all turned to stare at her as she stood there, clearly not expecting her to be there.

"OH DEAR," Mettaton sighed. "THERE GOES THE SURPRISE."

"PUNK," Undyne complained. "YOU WEREN'T SUPPOSED TO BE BACK FOR ANOTHER THIRTY MINUTES."

"Yo, Light." Kid said simply with a smile.

Light looked around the room, hopelessly confused. Not only did she have no idea where they would have gotten all this stuff, but she also had no idea what it was all for. Or why they had wanted her out of the house before it was ready.

"What is all this?" She asked slowly.

"It's your birthday party, silly." Kid said cheerfully.

"Birthday... party?"

"Well, not strictly a 'birthday' party." Sans clarified. "But, we decided to celebrate it like one."

Light just looked at them all in confusion. What, in the world, were they talking about?

"You do know what today is, don't you?" Toriel asked. "It's the anniversary of when you fell into the underground. The day you came into our lives."

Light stood there speechless as Toriel's words echoed in her head. Had it really been a whole year since that day? And even still, why were they making such a big deal out of it? She didn't see how her arrival would be so important. She was brought back to reality as Kid spoke up next to her.

"Mrs Toriel, can I give Light her present?" He asked excitedly.

"I don't see why not." She replied with a grin.

"Yes!" The armless monster dashed over to the table covered inn wrapped boxes, picking one up with his tail before dashing back to hand it to Light. "This one's from me."

Light took the wrapped box gingerly, almost as if she expected it to bite her. Then she carefully began to remove the colourful paper, revealing a small box that was usually used to hold jewellery. Opening that, she found a beautiful silver charm bracelet, without charms. Light pulled the silver chain out of the box, and simply held it for a few moments, before Sans helped her put it on.

"OPEN MINE NEXT, ANGEL LIGHT." Papyrus said excitedly, handing her a smaller wrapped box.

Within that, Light found a charm already on a clip ready to be added to her new bracelet. The charm was the shape of a skull, with orange and blue colourations to it. It almost seemed to glow as Light attached in to the silver chain. The next few gifts were similar. Light guessed that they must have coordinated who would give her which charm. Undyne's was a blue spear that almost seemed to ripple like water, Mettaton's was a purple lightning bolt, which also seemed to glow, Toriel's was a green snail that almost brought her to tears, Asgore's was a red fireball and Alphy's was a yellow cell phone. Flowey didn't have a present for her, but she wasn't bothered about it. Sans was the last to give his present.

"Here ya go, Sun-Light." He said with a grin.

Light took the sloppily wrapped gift in her hands, easily removing the paper to reveal a mass of thick, blue fabric and a familiar white symbol. Light held the light blue hoody in both hands, just staring and the royal family crest emblazoned on the back. She barely heard Sans speak as she was lost in her thoughts.

"Now you won't have to keep stealing mine." He said jokingly. "And those charms on your bracelet aren't just for show." Light looked up at him. "Everyone put a little bit of their magic into the charm they gave you. If you ever need to, you can use that magic as your own."

"They'll also act as a tracker. Once I get my machine to work." Alphyus added.

"WE KNOW YOU'VE BEEN STALLING ON MAKING CONTACT WITH THE HUMANS FROM THE NEARBY TOWN, PIPSQUEAK." Undyne said in an unusually gentle voice. "WE KNOW YOU'RE SCARED THAT THEY'LL TRY TO HURT US, OR TAKE YOU AWAY."

"We wanted to do something to cheer you up, and show you you're not alone," Monster Kid piped up. "And a birthday was perfect for that. But, since we don't know when your real birthday is, we decided... Light, are you okay?"

Light felt like her heart was about to explode from all the affection she was receiving. How did they always know when something was bothering her? She couldn't explain why, but even now after one year, it always took her by surprise how they could read and understand her so well.

She buried her face in the soft, blue fabric as hot tears stung her eyes and ran down her face, her small shoulders shaking with the effort to stop herself from sobbing. Swallowing a thick lump in her throat, she tried to speak.

"Thank you…" She began her voice cracking and wavering. "Thank you so much for this. I… didn't mean to start crying. But… it just suddenly hit me that… I have so many people that care about me… that understand me… Accept me… I don't know why but… It feels like it's been forever since I last felt something like this."

Monster kid walked up to the crying girl, wrapping his tail around her and resting his head on her shoulder in a hug. Then, one by one, everyone else in the room began to join in on the group hug. Light soon found herself sandwiched in the middle of the monsters, unable to move.

For what felt like the first time, Light felt safe.


End file.
